Effect of Pasteurization and Preservation Treatment on the Quality of “kunun zaki” made from Sorghum (Sorghum biocolor)

Abstract

Objective:This study was designed to determine the effect of pasteurization and preservation treatments on the shelf-life of “kunun zaki.” Materials and Methods: “Kunun zaki” was prepared from sorghum using improved method. The prepared “kunun” was divided into 9 equal portions. The 1^st four samples were pasteurized (10 – 25 minutes). The 2^nd four samples were pasteurized (10 – 25 minutes) and preserved with 120ppm of sodium metabisulphite each. The 9^th portion was the control. The samples were kept at ambient temperature (29±2°C) for nine weeks. The following parameters were monitored; protein content, ash, fibre, pH, specific gravity, microbial load. Means and standard deviation were calculated for triplicate determinations. Results: Proximate analysis showed that moisture content ranged between 88.20%-89.42%. Protein content ranged between 1.94-2.46% with the sample pasteurized for 25mins in combination with preservation having the highest protein content (2.46%). Ash and fibre contents were found to be low in all the samples. pH was acidic in all the samples ( pH 4.12-5.96). Specific gravity at week 0 was between 1.036 – 1.044, while at week 9 it ranged between 1.045 – 1.049. There was no microbial growth in all the samples at week 0. However at week 1 Microbial count of 2.0 x10⁴cƒμ/ml was observed in the control. At week 5, microbial growth in the range of 2.0 x 10³ – 3.5 x 10⁴ was observed in all the samples. Conclusion: Pasteurization treatment in combination witho preservation treatment had slightly higher protein contents than the control sample. They also had a longer stable shelf-life compared to the samples given pasteurization treatment only.

Keywords: “kunun zaki”, pasteurization, sodium metabisulphite, shelf-life, physical properties, proximate composition.